The younger dog seems to view the older dog as alpha bitch. Big problem, because she will certainly vie for that position if she perceives aging or weakness. Your daughter must be viewed as alpha bitch, with no wiggle room. Pleading, and/or bribes will quickly lessen that position. She must be viewed by both dogs as clear alpha. She must assert herself frequently, whether opportunities present or not. It couldn’t hurt to put both dogs through drills. It doesn’t have to be extensive, but should be regular. Admonition and treats should be in use. I would drill the dogs seperately at first, and then together, treating the one which does this best, admonishing the other. Both dogs will see that their treats, their scolding, their routine comes from the same place. You may want a professional to help. Failing a full training program, I would relocate one of the dogs. Or, go the shock collar route.. not a good choice.